The invention relates to a process and equipment for filling cavities with a flowable reaction mixture, wherein the reaction mixture is injected through an inlet opening located at the bottom of the cavity. In this connection, the preferred reaction mixtures are those that form polyurethane and particularly those forming foam materials. The cavities to be filled can be those of hollow profiles (i.e., between structural sheets) or molds.
In the past, when the reaction mixture was injected into the cavity, the hydrodynamic inclusion of air could not generally be avoided. This was particularly true where some of the mixture had to be injected at a higher pressure because of the short reacting time of the reaction mixture. Since the hydrodynamically entrapped air was released only at the end of the injection cycle, it was virtually impossible for the air to escape through the top in the hardened mixture, particularly in the case of long, thin cavities.
It was therefore an object of the instant invention to provide a process and apparatus whereby the inclusion of air bubbles in the reacted mixture and, consequently, in the finished part could be avoided.